{ "id": "cond-mat/0410427", "version": "v1", "published": "2004-10-17T21:04:03.000Z", "updated": "2004-10-17T21:04:03.000Z", "title": "Correlations in mesoscopic magnetic systems", "authors": [ "F. Gulminelli", "Ph. Chomaz" ], "categories": [ "cond-mat.stat-mech" ], "abstract": "The purpose of this proposal is to study the ferro/para phase transition in a mesoscopic Ising-like lattice and in particular demonstrate the existence of a negative magnetic susceptibility in the fixed magnetization ensemble. To this aim we will use the correlation < S(r) S(r+Dr) > = < M2>/N2 where N is the total number of spins for a single cluster, M the total magnetization of the cluster, and the equality holds if we choose r0